SECURING THE SKIES

Battle of Britain in Detail Part 3

The Birth of Radar

The advent of an aggressive potential enemy capable of threatening the UK so worried the Government that they set up a Committee for the Scientific Survey of Air Defence, with a membership that included several distinguished scientists. The very first meeting of this Committee in January 1935 heard a proposal from Mr (later Sir) Robert Watson-Watt of the National Physical Laboratory on the possibility of detecting aircraft using reflected radio waves – the principal of what is now known as radar. This required Treasury approval for the expenditure of some£10,000, but Air Marshal Sir Hugh Dowding, the senior officer responsible for research and development for the RAF, wisely considered that this would more probably be forthcoming if some basic evidence was available.

Dowding therefore arranged for an RAF aircraft to be made available to Watson-Watt. The latter, with help from AFWilkins, set up a crude experiment in the middle of a field near Weedon in Northamptonshire. At this location, on 26 February 1935, Watson-Watt and Wilkins parked a van with a radio receiver connected to antenna slung from wooden poles and linked to a cathode ray oscilloscope. Meanwhile, Flight Lieutenant RS Blucke approached the nearby town of Daventry in a venerable Handley-Page Heyfordbiplane bomber. Blucke proceeded to fly a predetermined route backwards and forwards between Weedon and Daventry, where there was a BBC Radio short-wave transmitter. In the field below, the receiver was tuned to the signal from the BBC, which showed as a straight line on the oscilloscope; however, as Blucke’s aircraft passed, it reflected the radio waves, producing a distinct spike on the oscilloscope trace.

Having scraped the mud off his shoes, Watson Watt wrote a memo entitled “Detection and Location of Aircraft by Radio Methods” and presented it to the Air Ministry the next day. Radar was born. Much work and further experimentation was necessary to turn this first, very crude, almost comical experiment, involving two men sitting in a van in the middle of a muddy field, into a functional early warning system integrated in to the UK’s air defences. Nevertheless, this most humble of beginnings was to have the most profound effect on the outcome of the Battle of Britain. Dowding duly got his money from the Treasury, and that notoriously parsimonious organisation actually sanctioned expenditure of £12,300 in the first year; much more was to follow.

The experiments continued, a research station was established for Watson Watt and a team of scientists at Bawdsey Manor in Suffolk, and the Treasury approved the construction of an experimental chain of five radar stations to cover the Thames Estuary. Perhaps the mandarin’s were persuaded to loosen the purse strings when the Air Ministry suspended all expenditure on the acoustic mirrors it had been building. Despite many hiccups and setbacks, the senior officers of the RAF were convinced by 1937 that a full chain of radar stations should be built to protect the east coast, and the government agreed. By the outbreak of War in September 1939, 20 radar stations were in operation, and further expansion followed under the impetus of live hostilities; 27 more radars were operational before the Battle of Britain.

Experiments had also been conducted at the other end of the “system”, whereby the plots originating at the radar stations were displayed on the operations room map tables at the newly established Fighter Command, and at Group and Sector headquarters lower down the chain*, interception orders then being passed by radio telephone to squadron commanders in the air. In addition to building the radar stations, all the necessary communications facilities had to be installed, linking radars, Observer posts and Observer Corps centres with Fighter Command Headquarters at Bentley Priory, near Stanmore, and connecting the Fighter Command operations room with Group and Sector operations rooms. All this work was done by the telephone engineers of the GPO.